This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A171053 #11 Mar 31 2017 00:45:56
%S A171053 2,3,5,7,11,13,17,14,23,24,31,37,91,93,97,53,54,61,67,71,73,74,83,84,
%T A171053 47,101,103,107,104,113,127,131,137,134,194,151,157,163,167,173,174,
%U A171053 181,141,143,147,144,211,223,227,224,233,234,291,251,257,263
%N A171053 In the sequence of prime numbers, replace all the '9' digits with '4' and vice versa.
%H A171053 Vincenzo Librandi, <a href="/A171053/b171053.txt">Table of n, a(n) for n = 1..1000</a>
%t A171053 FromDigits[IntegerDigits[#] /. {9 -> p, 4 -> q} /. {p -> 4, q -> 9}] & /@ Prime[Range[100]] (* _Vincenzo Librandi_, Apr 07 2013 *)
%o A171053 (PARI) a(n)=my(v=[0,1,2,3,9,5,6,7,8,4]);subst(Pol(apply(k->v[k+1], digits(prime(n)))),'x,10) \\ _Charles R Greathouse IV_, Jul 31 2013
%K A171053 nonn,base,easy
%O A171053 1,1
%A A171053 _N. J. A. Sloane_ and _Vincenzo Librandi_, Sep 04 2010